Java: Write a class encapsulating the concept of a circle, assuming a circle has
ID: 3593840 • Letter: J
Question
Java:
Write a class encapsulating the concept of a circle, assuming a circle has the following:
two fields: a point which is an object of type Point (from java.awt package) representing the center of the circle, and the radius (int) of the circle
secondary constructor (default constructor should not be implemented)
accessor methods for each field
mutator methods for each field
toString method
equals method
a "business" method calculating and returning the primeter of the circle (2 * * radius)
a "business" method calculating and returning the area of the circle ( * radius2)
write a client class to test all the methods in your class
Explanation / Answer
import java.awt.Point;
/**
* @author pravesh
*
*/
public class Circle {
// instance variables
private double radius;
private Point centre;
private static final double PI = 3.14159;
// constructors
public Circle() {
radius = 0;
}
/**
* @param radius
*/
public Circle(double radius) {
this.radius = radius;
}
// getters and setters
/**
* @return radius
*/
public double getRadius() {
return radius;
}
/**
* @param radius
*/
public void setRadius(double radius) {
this.radius = radius;
}
/**
* @return area
*/
public double getArea(){
return PI*radius*radius;
}
public Point getCentre() {
return centre;
}
public void setCentre(Point centre) {
this.centre = centre;
}
/**
* @return perimeter
*/
public double getCircumference(){
return 2*PI*radius;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return "Radius: "+radius+", Center: "+centre;
}
@Override
public boolean equals(Object obj) {
if(obj instanceof Circle) {
Circle c = (Circle)obj;
if(c.centre.equals(centre) && c.radius == radius)
return true;
}
return false;
}
}
##########
import java.awt.Point;
public class CircleDriver {
public static void main(String[] args) {
Circle c = new Circle();
c.setCentre(new Point(3, 2));
c.setRadius(6);
System.out.println("Area: "+c.getArea());
System.out.println("Circumference: "+c.getCircumference());
System.out.println(c);
}
}
/*
Sample run:
Area: 113.09723999999999
Circumference: 37.699079999999995
Radius: 6.0, Center: java.awt.Point[x=3,y=2]
*/
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